The polyphenylene oxides and methods for their preparation are known in the art and are described in numerous publications, including Hay U.S. Pat. No. 3,306,874 and 3,306,875. The Hay processes are based on the use of copper-amine complexes. Polymerization techniques for the preparation of polyphenylene oxides are disclosed in McNelis, U.S. Pat. No. 3,220,979; Olander, U.S. Pat. No. 3,956,242; Nakashio, U.S. Pat. No. 3,573,257; and Nakashio, U.S. Pat. No. 3,787,361. Some of the prior art oxidative coupling reactions are based on the stoichiometric oxidation of PbO.sub.2 and MnO.sub.2 which do not function as catalysts in those processes.
In the applicant's copending applications Ser. No. 491,370 filed July 24, 1974 and Ser. No. 534,903, filed Dec. 20, 1974, there are disclosed novel procedures for polymerizing polyphenylene oxides with complex manganese based catalysts. All of these patents and applications are hereby incorporated by reference.
The procedures which have employed manganese based catalysts have been based on the use of both complexed and uncomplexed catalysts that form substantially homogeneous type polymerization mixtures. These mixtures are usually subjected to a batch type bulk polymerization and after the polymer reaches the desired molecular weight, the reaction is terminated. The catalyst or polymer must be separated from the reaction mixture by means of an antisolvent or extraction-separation technique which results in catalyst losses that prevent reuse of the catalyst and add substantially to the cost of the process. Accordingly it would be advantageous to prepare an active catalyst that is heterogeneous with a solution of a phenolic monomer so that a fixed bed polymerization process may be carried out. This type or process may be operated continuously, eliminates the need to separate the polymer-catalyst mixture and permits reuse of the heterogeneous catalyst composition. Should the bed begin to lose its activity after a period of operation, re-coordination of the lost manganese should restore the catalyst bed to its former efficiency.
It has been found that a useful heterogeneous catalyst for the oxidative coupling of phenolic monomers comprises a manganese complex that is formed from a manganese (II) compound and a crosslinked vinyl resin having units that contain a benzoin oxime group. These catalysts may be used in a fixed bed and substantially eliminates the need to carry out a separate separation step to obtain the polymer solution free of catalyst.
Accordingly, it is a primary object of this invention to provide a heterogeneous catalyst system for the polymerization of phenolic monomers into polyphenylene oxide resins.
It is also a further object of this invention to provide a heterogeneous polymer-bound catalyst system that includes complexed manganese.